As for a technique for adjusting an inclination of a probe card, there is known, e.g., an adjusting mechanism for a probe card which is suggested in Patent Document 1 by the applicant of the present invention. In this technique, when electrical characteristics of an object to be inspected such as a semiconductor wafer W or the like are inspected by using a plurality of probes, needle tips of the probes provided at the probe card are imaged in several locations by using a camera, and heights of tip positions of the probes are detected. Based on the difference in the tip heights of the probes, the inclination of the probe card is obtained and, then, the inclination of the probe card is adjusted.
As a pre-processing for detecting the tip heights of the probes by using the camera, coordinates of a reference position of a wafer chuck 1 are obtained by moving the wafer chuck 1 via an XY table 2 and aligning a focus of a second camera 4 that has reached a probe center and a focus of a first camera 3 attached to the wafer chuck 1 with a target 5 attached to the wafer chuck 1, as shown in, e.g., FIG. 5A.
Next, the wafer chuck 1 moves from the reference position to a position below a probe card 6. As illustrated in FIG. 5B, the focus of the first camera 3 is aligned with a tip of a specific probe 6A of the probe card 6, thereby obtaining XYZ coordinates of a height of a tip position of the corresponding probe 6A. Then, the wafer chuck 1 moves to, e.g., three different locations, and the heights of tip positions of the probes 6A in the respective locations are obtained.
If the tip heights of the probes 6A are the same in four locations, it means that the probe card 6 has been levelly disposed so that the probe card 6 can be used for inspection without inclination adjustment. However, if the tip heights of the probes 6A are not the same in the four locations, the probe card 6 is made to be at a level with the mounting surface of the wafer chuck 1 by adjusting the inclination of the probe card 6 (level adjustment) based on the height differences, as can be seen from FIG. 5C. After the inclination of the probe card 6 is adjusted, as depicted in FIG. 5D, the tip heights of the probes 6A of the probe card 6 in the four locations are obtained, thus checking whether or not there exists height difference. When the height difference exists, the inclination of the probe card 6 is adjusted based on the height difference (see FIG. 5C). When all of the probes 6A become at a level with the wafer chuck 1, the level adjustment of the probe card 6 is completed.
[Patent Document 1] Japanese Patent Laid-open Application No. 2005-140662
Since, however, the probe card 6 is provided with a plurality of probes 6A, the tip heights of the probes 6A are not necessarily the same. Namely, the probes 6A have variation in the heights of the tip positions thereof. For that reason, when the heights of tip positions of several representative probes 6A (e.g., four probes in four corners) are detected by using the first camera 3, the variation in the heights of the tip positions thereof affects the detection and, also, the height may be miscalculated due to residues of aluminum adhered to the needle tips, which adversely affects the adjustment of the probe card 6. Further, when the heights of the needle tip positions of the probes 6A are detected by using the first camera 3, a long period of time is required to align the focus of the camera with the needle tip of the probes 6A.